1. Field of the Invention
The present invention relates generally to heat exchangers for motor vehicles and, more specifically, to a continuous combination fin for a heat exchanger in a motor vehicle.
2. Description of the Related Art
It is known to provide a louvered fin for a heat exchanger such as an evaporator in a motor vehicle. An example of such a louvered fin is disclosed in U.S. Pat. No. 5,738,168. The louvered fin typically is a corrugated fin having generally planar walls joined in a xe2x80x9cVxe2x80x9d shape at crests. The louvered fin also has a plurality of louvers bent integrally out of the walls at an angle for the purpose of breaking up airflow over the fins and increasing heat transfer. Further, the louvered fin may have multiple louvers in which the louvers are divided into a pattern of alternating, adjacent sets of louvers to guide airflow in an attempt to induce turbulent flow therein. Commonly, two sets of louvers are used, an entrance set and an exit set separated from one another by a central portion. When air flows over the walls of the louvered fin, the airflow will engage the louvers of the entrance set and be deflected upwardly through the wall at the angle of the entrance set of louvers. Air in the deflected stream flows between a pair of adjacent central portions in two adjacent walls. The air is deflected back through the louvers of the exits set in the same way. It should be appreciated that the airflow has a generally shallow bell curve shape.
Another known louvered fin for a heat exchanger such as an evaporator is disclosed in U.S. Pat. No. 4,580,624. In this patent, groups of louvers are sloped alternately or in different combinations on the fin.
It is also known to provide an off-set strip fin for a heat exchanger. An example of such a fin is disclosed in U.S. Pat. No. 4,615,384. In this patent, the off-set strip fin has a wall with plurality of louvers. separated by a fixed distance from the wall. The louvers are staggered, i. e. arranged alternately on an upper side and a lower side of the wall, so that each pair of louvers adjacent to each other give rise to an empty space for water discharge.
Other examples of known fins for heat exchangers are disclosed in U.S. Pat. No. 3,214,954 and Japanese Patent No. 10-141805. U.S. Pat. No. 3,214,954 discloses a fin roll and Japanese Patent No. 10-141805 discloses a multi-stage fin.
Although the above fins have worked for an evaporator, the louvered fin outperforms the off-set strip fin in heat transfer. On the other hand, the off-set strip fin outperforms the louvered fin in water shedding. Also, the turnaround rib is the weakest heat transfer area of the louvered fin. Therefore, there is a need in the art to provide a continuous combination fin for a heat exchanger that outperforms conventional fins in both heat transfer and water shedding.
Accordingly, the present invention is a continuous combination fin for a heat exchanger including a base wall having a first portion, a second portion and a third portion. The continuous combination fin also includes a plurality of entrance louvers in the first portion extending outwardly at an angle in a first direction from the base wall. The continuous combination fin includes a plurality of exit louvers in the third portion extending outwardly at an angle in a second direction from the base wall reversed from the first direction. The continuous combination fin further includes a plurality of drainage louvers in at least one of the first portion and the second portion and the third portion that are off-set relative to each other such that air flows through the entrance louvers and exit louvers and water drains through the drainage louvers.
One advantage of the present invention is that a continuous combination fin for a heat exchanger such as an evaporator is provided for a motor vehicle. Another advantage of the present invention is that the continuous combination fin promotes water drainage and enhances heat transfer. Yet another advantage of the present invention is that the continuous combination fin provides two types of louvers to obtain the best performance of both the louvered fin and off-set strip fin. Still another advantage of the present invention is that the continuous combination fin provides a relatively large louver angle and a relatively small louver pitch. A further advantage of the present invention is that the continuous combination fin provides a flexible fin roll that can have a family of three or more different combinations.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.